Methods and apparatus to monitor a channel to determine neighbor cell information

ABSTRACT

Methods and apparatus to monitor a channel to determine neighbor cell information are disclosed. An example method for a first mobile station to determine cell information for a first cell disclosed herein comprises monitoring a channel for messages containing cell information, receiving a first message via the monitored channel and addressed to a second mobile station, the first message including first cell information, and storing the first cell information for a time period after receiving the first message.

FIELD OF THE DISCLOSURE

This disclosure relates generally to neighbor cell informationprocessing and, more particularly, to methods and apparatus to monitor achannel to determine neighbor cell information.

BACKGROUND

Neighbor cell information is used to facilitate mobility in many typesof communication systems, such as a communication system compliant withthe GSM/EDGE radio access network (GERAN) specifications (where GSMrefers to “global system for mobile communications” and EDGE refers to“enhanced data rates for GSM evolution”). In a GERAN communicationsystem, network cell system information is used by a mobile station toperform mobility procedures including, but not limited to, cellreselection and delayed call re-establishment. For example, in some cellreselection operating modes, such as when network assisted cell change(NACC) is enabled, the mobile station's serving cell provides the mobilestation with neighbor cell system information for the target neighborcell (or potential target cell or cells) of the reselection procedure.The mobile station can then use this neighbor cell system information toaccess the target neighbor cell directly upon reselection, withouthaving to first receive messages broadcast in the target cell containingthe target cell's system information. However, in a conventionalimplementation, after reselection is triggered, the network typicallyprovides and the mobile station typically waits to receive a sufficientset of neighbor cell system information before concluding thereselection procedure to acquire the target neighbor cell.

In a GERAN communication system supporting call re-establishment, amobile station experiencing a radio link failure during a call canre-establish the call with a neighbor cell without user intervention,provided the mobile station can acquire and establish a connection withthe target neighbor call within a specified time period. However, in aconventional implementation, the mobile station typically waits toreceive some or all of the system information broadcast by the targetneighbor cell before initiating call re-establishment. The time taken toreceive the target cell's broadcast system information can consume asignificant amount of the specified completion time period and, thus,impact whether call re-establishment can be completed successfully.Reselection and call re-establishment are but two examples of mobilityprocedures in which a mobile station in a conventional GERAN systemtypically waits to receive sufficient neighbor cell system informationfrom a serving cell or the neighbor cell itself before concluding themobility procedure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example communication system supportingneighbor cell information processing according to the methods andapparatus described herein.

FIG. 2 is a message sequence diagram illustrating a prior art cellreselection procedure involving network assisted cell change (NACC) thatcould be performed by the communication system of FIG. 1.

FIG. 3 is a message sequence diagram illustrating example channelmonitoring for neighbor cell information and subsequent avoidance oftransmission of redundant neighbor cell information that can be used ina cell reselection procedure performed by the communication system ofFIG. 1.

FIG. 4 is a message sequence diagram illustrating a prior art delayedcall re-establishment procedure that could be performed by thecommunication system of FIG. 1.

FIG. 5 is a message sequence diagram illustrating example channelmonitoring to determine neighbor cell information for use in a delayedcall re-establishment procedure performed by the communication system ofFIG. 1.

FIG. 6 is a block diagram of an example mobile station that could beused to implement a part of the communication system of FIG. 1.

FIG. 7 illustrates a first example neighbor cell data combiningoperation performed by the mobile station of FIG. 6.

FIG. 8 illustrates a second example neighbor cell data combiningoperation performed by the mobile station of FIG. 6.

FIG. 9 is a block diagram of an example network element, such as a basestation controller, that could be used to implement a part of thecommunication system of FIG. 1.

FIG. 10 is a flowchart representative of an example channel monitoringprocess that may be performed to implement the mobile station of FIG. 6or the communication system of FIG. 1, or both.

FIG. 11A is a flowchart representative of an example neighbor cellvalidity indication process that may be performed to implement themobile station of FIG. 6 or the communication system of FIG. 1, or both.

FIG. 11B is a flowchart representative of another example neighbor cellvalidity indication process that may be performed to implement themobile station of FIG. 6 or the communication system of FIG. 1, or both.

FIG. 12 is a flowchart representative of an example network process thatmay be performed to implement the network element of FIG. 9 or thecommunication system of FIG. 1, or both.

FIG. 13 is a block diagram of an example processing system that mayexecute example machine readable instructions to implement some or allof the processes of FIGS. 10-12 to implement some or all of the mobilestation of FIG. 6, the network element of FIG. 9 and the communicationsystem of FIG. 1.

DETAILED DESCRIPTION

Methods and apparatus to monitor a channel to determine neighbor cellinformation are disclosed herein. An example technique described hereinfor a first mobile station to determine cell information for a firstcell involves the first mobile station monitoring a channel for messagescontaining cell information. This example technique also involvesreceiving a first message including first cell information via themonitored channel, but with the first message addressed to a secondmobile station. In an example implementation, the first mobile stationstores the first cell information for a time period after receiving thefirst message.

Methods and apparatus to use such determined neighbor cell information,or other obtained neighbor cell information, or both, to avoidtransmission of redundant neighbor cell information to mobile stationsare also disclosed herein. A first example technique to avoidtransmission of redundant neighbor cell information from a network to amobile station involves the mobile station setting a validity indicationrepresenting whether the mobile station has valid neighbor cellinformation associated with a neighbor cell. This example technique alsoinvolves the mobile station sending the validity indication to thenetwork to indicate whether the network can omit subsequent sending ofat least a portion of the neighbor cell information associated with theneighbor cell to the mobile station.

A second example technique to avoid transmission of redundant neighborcell information from a network to a mobile station involves the networkreceiving a validity indication from the mobile station representingwhether the mobile station has valid neighbor cell informationassociated with a neighbor cell. This example technique also involvesthe network determining whether to schedule sending of the neighbor cellinformation associated with the neighbor cell to the mobile stationbased on the received validity indication.

As described in greater detail below, in a particular exampleimplementation of any of the preceding techniques, a mobile station canobtain neighbor cell information by monitoring for messages addressed toitself and other mobile stations conveyed via a channel, such as ashared channel, a multiplexed channel, a channel accessible by multiplemobile stations or, in other words, via which data packets can beaddressed to particular mobile stations, etc. For example, in a GERANcommunication system, the mobile station can monitor a packet associatedcontrol channel (PACCH) for messages containing or otherwise related tothe provisioning of neighbor cell information, such as packet neighborcell data (PNCD) messages, packet cell change continue (PCCC) messages,packet cell change order (PCCO) messages, or packet switched handover(PSHO) messages. Additionally, in such a GERAN communication system, themobile station can send measurement reports to the network containingsystem information validity indications in the form of one or more bitsor bitmaps to inform the network that the mobile station has validstored neighbor cell system information for one or more neighbor cells.The valid stored neighbor cell system information can be obtained bymonitoring the PACCH for PNCD messages containing neighbor cell systeminformation, by receiving system information messages broadcast by theneighbor cell(s), from any other source, etc., or any combinationthereof. Upon receiving such system information validity indications,the network can determine whether it can omit sending at least some ofthe neighbor cell information to the mobile station because suchinformation would be redundant with the valid neighbor cell informationalready stored in the mobile station.

As described in greater detail below, GERAN communication systems,mobile stations and network elements implementing the example techniquesdescribed herein can exhibit substantial benefits over conventionalGERAN communication systems, mobile stations and network elements. Forexample, in conventional GERAN systems, a mobile station is unable toreceive, store and use neighbor cell information specifically addressedto another mobile station. In contrast, in a GERAN communication systemimplementing the example techniques described herein, a mobile stationis able to receive, store and use neighbor cell information even if suchinformation is addressed to another mobile station. Additionally, in atleast some cell reselection scenarios, a conventional GERAN networktypically sends complete neighbor cell information for one or moreneighbor cells to a mobile station, even if some or all of this neighborcell information is already stored in the mobile station. In contrast, aGERAN communication system implementing the example techniques describedherein enable the GERAN network to avoid sending such redundant neighborcell information. As such, the benefits associated with the exampletechniques described herein can include, but are not limited to,reducing the radio resources consumed by sending redundant neighbor cellinformation, reducing the time spent completing cell reselection,reducing the time spent re-establishing a call experiencing a radio linkfailure when call re-establishment is enabled, increasing the likelihoodthe call re-establishment will be successful, etc.

Turning to the figures, a block diagram of an example GERANcommunication system 100 capable of supporting the neighbor cellinformation processing techniques described herein is illustrated inFIG. 1. The GERAN system 100 includes a base station controller (BSC)105 in communication with three base station transceivers (BTSs) 110,115 and 120 implementing three respective cells: cell 1, cell 2 and cell3. Additionally, the BTS 110 implementing cell 1 in the illustratedexample is in communication with three mobile stations (MSs) 125, 130and 135. As described in greater detail below, the BSC 105 (e.g.,possibly in conjunction with the BTSs 110-120) and one or more of theMSs 125-135 implement the example techniques to monitor channels todetermine neighbor cell information. Additionally or alternatively, theBSC 105 (e.g., possibly in conjunction with the BTSs 110-120) and one ormore of the MSs 125-135 implement the example techniques to avoidtransmission of redundant neighbor cell information to mobile stationsdescribed herein.

In the GERAN system 100 of FIG. 1, the mobile station 105 may beimplemented by any type of mobile station or user endpoint equipment,such as a mobile telephone device, a mobile telephone deviceimplementing a stationary telephone, a personal digital assistant (PDA),etc. Additionally, although each BTS 110, 115 and 120 implements arespective cell in the illustrated example, one or more of the BTSs 110,115 and 120 could be configured to implement multiple cells.Furthermore, although only one BSC 105, three BTSs 110-120 and three MSs125-135 are illustrated in FIG. 1, the GERAN system 100 can support anynumber of BSCs, BTSs and MSs. For example, the GERAN system 100 cansupport multiple BSCs in communication with each other and capable ofexchanging neighbor cell system information.

In the illustrated example of FIG. 1, the MSs 125-135 are each operatingin a mode supporting packet data communications. As such, the BSC 105and the BTS 110 of the GERAN system 100 have allocated a PACCH channel140 to convey downlink messages to one or more of the MSs 125-135. ThePACCH channel 140 is configured to convey distribution messagesbroadcast to one or more of the MSs 125-135, and non-distributionmessages addressed to a particular one of the MSs 125-135. Generally,each MS 125-135 is permitted to retain and use any distribution (e.g.,broadcast) message conveyed via a PACCH 140 to which it is allocated.However, unless explicitly permitted, a particular MS 125-135 ispermitted to retain and use only those non-distribution (e.g.,non-broadcast) messages conveyed via the PACCH 140 that are specificallyaddressed to the particular MS 125-135. In other words, a particular MS125-135 is to discard any non-distribution (e.g., non-broadcast)information conveyed via the PACCH 140 after determining the message isnot specifically addressed to the MS 125-135.

The GERAN system 100 uses the PACCH 140 to convey, among other things,neighbor cell information to the MSs 125-135 to facilitate variousmobility procedures. For example, cell 1 (implemented by BTS 110) canuse the PACCH 140 to convey messages, such as non-distribution PNCDmessages defined in the GERAN specifications, to any, some or all of theMSs 125-135 containing neighbor cell information for any or all of cell2 (implemented by BTS 115) or cell 3 (implemented by BTS 120). Suchneighbor cell information can take the form of one or more systeminformation (SI) messages, such as SI messages SI-1, SI-3 and SI-13defined in the GERAN specifications, associated with each respectiveneighbor cell. Conventionally, because a PNCD message containingneighbor cell information (e.g., SI messages) is a non-distributionmessage, only the MS 125-135 to which the PNCD message is addressed canretain the included neighbor cell information (e.g., PNCD messagesdetermined to be addressed to another MS are to be discarded). However,in the GERAN system 100 implementing the example techniques to monitorchannels for neighbor cell information described herein, a particular MS125-135 can also retain neighbor cell information included in PNCDmessages conveyed via the PACCH 140 but addressed to other of the MSs125-135.

Other messages related to the provisioning of neighbor cell informationthat can be conveyed via the PACCH 140 include PCCC messages, PCCOmessages and PSHO command messages, as defined in the GERANspecifications. Processing of PNCD, PCCC, PCCO and PSHO messages, aswell as other messages, conveyed via the PACCH 140 is described ingreater detail below.

To support uplink communications from the MSs 125, 130 and 135, theGERAN system 100 includes respective uplink channels 145, 150 and 155.The uplink channels 145, 150 and 155 can be implemented by any type ofchannel, such as one or more shared (common) channel or channels, one ormultiplexed channels, one or more dedicated channel or channels, or anycombination thereof. As described in greater detail below, in the GERANsystem 100 implementing the example techniques to avoid transmission ofredundant neighbor cell information described herein, a particular MS125-135 can use its respective uplink channel 145-155 to send a validityindication to the network (e.g., to cell 1 as implemented by the BTS 110and BSC 105) to indicate what, if any, neighbor cell information (e.g.in the form of SI messages or their contents) is already stored in theparticular MS 125-135. Such stored neighbor cell information can beobtained by monitoring distribution or non-distribution messages on thePACCH 140 as described in greater detail below, by receiving broadcastmessages from one or more neighbor cells, or by other techniques, etc.,or any combination thereof. The network can then use the receivedvalidity indication according to the example techniques described belowto determine whether to schedule subsequent sending of any, some or allof the neighbor cell information associated with any, some or all of theneighbor cells (e.g., cells 2 or 3, or both) to the particular MS125-135 (e.g., via one or more PNCD messages conveyed via the PACCH140).

For brevity and clarity, operation of the GERAN system 100 to implementthe example techniques to monitor channels for neighbor cell informationand the example techniques to avoid transmission of redundant neighborcell information are described from the perspective of the MS 125operating in cell 1 as implemented by the BTS 110 in conjunction withthe BSC 105. However, it can be readily appreciated that these exampletechniques can be implemented by any of the MSs 125-135 operating in anyof the cells implemented by any of the BTSs 110-120 in conjunction withthe BSC 105 and possibly other BSCs (not shown). Furthermore, althoughthe example techniques to monitor channels for neighbor cell informationand the example techniques to avoid transmission of redundant neighborcell information are described in the context of the GERAN system 100 ofFIG. 1, these example techniques can be readily adapted for use in anycommunication system in which neighbor cell information is conveyed viaa channel.

To provide context for the example techniques to monitor channels forneighbor cell information and the example techniques to avoidtransmission of redundant neighbor cell information described herein, aprior art cell reselection operation that could be implemented in theGERAN system 100 is illustrated in the message sequence diagram of FIG.2. In particular, FIG. 2 illustrates a prior art cell reselectionoperation in which network assisted cell change (NACC) is enabled.

As defined in the GERAN specifications, there are three possible networkcontrol modes, NC0, NC1 and NC2, under which cell reselection can beperformed. From the perspective of the MS 125 operating in cell 1 of theGERAN system 100 as implemented by the BTS 110 in conjunction with theBSC 105, NC0 mode corresponds to a completely autonomous mode in whichcell reselection is performed autonomously by the MS 125 (e.g., with theMS 125 selecting the target neighbor cell for reselection withoutproviding any measurement reports to the network). NC1 mode correspondsto a partially autonomous mode in which autonomous cell reselection bythe MS 125 is permitted, and the MS 125 is to also send measurementreports to the network. Conversely, in NC2 mode, the network controlscell reselection and selects the target neighbor cell based onmeasurement reports sent by the MS 125. In general, autonomousreselection by the MS 125 is not permitted in NC2 mode. The networkcontrol modes NC0, NC1 and NC2 are applicable to the MS 125 whenoperating in a packet transfer mode or an idle mode.

Additionally, in the NC0 and NC1 modes, NACC may be enabled for aparticular MS, such as the MS 125. NACC includes two aspects: cellchange notification (CCN) performed by the MS, and distribution ofneighbor cell information by the network. These may be usedindependently of each other. For example, if the CCN aspect of NACC isenabled, the MS 125 is to use a packet cell change notification (PCCN)message to inform the network when autonomous reselection to aparticular target neighbor cell is possible (e.g., such as when one ormore autonomous reselection criteria are met). When the PCCN message isreceived from the MS 125 by the network, the network can respond byproviding the MS 125 with neighbor cell system information for theproposed target cell included in the received PCCN message.Alternatively, the network can provide neighbor cell system informationfor another neighbor cell if the network decides to override theproposed target cell indicated in the received PCCN message. Suchneighbor cell system information can be provided by the network usingone or more PNCD messages conveyed to the MS 125 via the PACCH 140.Additionally, after having received a PCCN, the network can determine tocomplete sending any ongoing data packets to the MS 125 before sending aPCCC message to the MS 125 confirming the proposed target cell orsending a PCCO message instructing the MS 125 to perform reselection tothe same or another specified target cell.

NACC enables the network to provide neighbor cell system information fora cell reselection target cell to the MS 125 typically faster than theMS 125 could obtain this information by receiving and processing SImessages broadcast by the target sell itself. As mentioned above, afterreselection is triggered but prior to concluding reselection to acquirethe target cell, the serving cell (e.g., cell 1) in communication withthe MS 125 sends the target cell's system information to the MS 125using one or more PNCD messages conveyed via the PACCH 140. The PNCDmessages are then followed by a PCCC or PCCO message, as appropriate.The network also conveys target neighbor cell system information to theMS 125 via one or more PNCD messages when a packet switched handover isto be performed. As such, PNCD messages can be used to convey neighborcell system information to the MS 125 in NC0, NC1 or NC2 mode.

Turning to FIG. 2, the message sequence diagram 600 illustrates messagesthat could be exchanged between the MS 125 and cells 1 and 2 of theGERAN network 100 if configured to implement a prior art cellreselection operation in which NACC is enabled. In FIG. 2, cell 1, asimplemented by the BSC 105 and the BTS 110, is represented by block 205,and cell 2, as implemented by the BSC 105 and the BTS 115, isrepresented by block 605. The illustrated message sequence diagram 600begins with the MS 125 being in idle mode and camped on cell 2(represented by the hollow directed line 610). Because the MS 125 iscamped on cell 2, the MS 125 is able to receive system informationmessages 612, 614 and 616 corresponding, respectively, to SI messagesSI-1, SI-3 and SI-13 being broadcast by cell 2.

Next, at block 618 the MS 125 performs cell reselection to cell 1. As aresult, MS 125 then camps on cell 1 (represented by the hollow directedline 620) and, thus, cell 1 becomes the serving cell for the MS 125.Sometime later, an uplink (UL) temporary block flow (TBF) and a downlink(DL) TBF are established between the MS 125 and cell 1 (represented bythe hollow directed line 622) and the MS 125 transitions from idle modeto packet transfer mode (PTM) in which packet data traffic can beexchanged with the network. A TBF (uplink or downlink) is a temporaryconnection established between the MS 125 and cell 1 to allow radio linkcontrol (RLC) and medium access control (MAC) packet data to beexchanged between the MS 125 and cell 1 over an allocated channel. Anuplink TBF conveys uplink RLC/MAC data from the MS 125 to the network(e.g., cell 1), and a downlink TBF conveys RLC/MAC data from the network(e.g., cell 1) to the MS 125. A particular TBF is identified using atemporary flow indicator (TFI) that uniquely identifies the TBF amongthose TBFs in the same direction and using the same timeslot(s) or, inother words, using the same packet data channel(s) (PDCH(s)). Forexample, in a GERAN-compliant system, a PDCH is associated with aparticular radio timeslot index, and a TBF may be implemented using oneor more PDCHs. For example, in a basic transmission time interval (BTTI)configuration, a TBF may be implemented using a single PDCH and, thus,be associated with a single timeslot index. However, in a reducedtransmission time interval (RTTI) configuration, a TBF may beimplemented using one or more pairs of PDCHs and, thus, be associatedwith one or more corresponding pairs of timeslot indices. Generally, aTFI value for a particular TBF is assumed to be unique among theconcurrent TBFs operating in the same direction (i.e., uplink ordownlink) and on the PDCH(s) used to implement the particular TBF.However, the same TFI value may be used to identify other TBFs operatingin the same direction but implemented using other PDCHs, or to identifyother TBFs operating in the opposite direction. As such, the TFI can beused to address RLC/MAC data packets conveyed using the associated TBFto a particular endpoint (e.g., the MS 125 of cell 1).

After the uplink TBF is established, the MS 125 is able to send ULRLC/MAC data blocks 624-626 to cell 1. Similarly, after the downlink TBFis established, cell 1 is able to send DL RLC/MAC data blocks (notshown) to the MS 125. Sometime later, the MS 125 triggers autonomousreselection in response to detecting one or more autonomous reselectioncriteria (block 628). Next, the MS 125 sends a PCCN message 630 to cell1 (its serving cell) to indicate that the criteria autonomousreselection are met. Furthermore, the MS 125 indicates in the PCCNmessage 630 that cell 2 is the proposed target neighbor cell. BecauseNACC is enabled, receipt of the PCCN message 630 may cause cell 1 tocoordinate with cell 2 (e.g., via the BSC 105) to obtain neighbor cellsystem information for cell 2 (represented by the hollow directed line632), if such information is not already available. UL and DL RLC/MACdata blocks 634-642 continue to be exchanged between the MS 125 and cell1 until the cell is ready to convey the neighbor cell system informationfor cell 2 to the MS 125.

In the message sequence diagram 600 of FIG. 2, cell 1 is able to beginsending PNCD messages containing neighbor cell information for cell 2 tothe MS 125 in the next radio block period after receiving the PCCNmessage 630. Here, two UL slots and two DL slots have been allocated forcommunications between the MS 125 and cell 1. Accordingly, cell 1 isable to send only two PNCD messages 644 and 646 in the radio blockperiod following receipt of the PCCN message 630. As shown, the PNCDmessages 644 and 646 are used to convey SI messages SI-1 and SI-3,respectively, for cell 2 (the proposed target cell identified in thePCCN message 630). UL RLC/MAC data blocks 648-650 are then exchanged inthe next radio block period, followed by cell 1 being able to finishsending the neighbor cell information for cell 2 by sending a PNCDmessage 652 containing SI message SI-13 for cell 2. Cell 1 can use theother allocated DL slot to send another DL RLC/MAC data block 654 to theMS 125. As described in greater detail below, although SI messages areshown in FIG. 2 as being contained completely in respective PNCDmessages, SI messages may be larger than, smaller than or equal to thepayload capacity of a PNCD message.

In the next radio block period, the MS 125 is able to send UL RLC/MACdata blocks 656-658 in its two allocated UL slots. In the correspondingDL slots, cell 1 sends a DL RLC/MAC data block 660 followed by a PCCCmessage 662. As described above, the PCCC message 662 indicates that theMS 125 can perform reselection to the proposed target cell (e.g., cell 2in FIG. 2). Alternatively, instead of sending the PCCC message 662, cell1 could decide to send (i) a PCCO message to specify a cell reselectiontarget cell different from the proposed target neighbor cell identifiedin the PCCN message 630, (ii) a PCCO message to provide furtherinformation specifying the behavior of the MS 125 in the proposed targetneighbor cell identified in the PCCN message 630, (iii) a PSHO commandmessage to indicate that the MS 125 is to perform packet switchedhandover to a specified target cell that may be the same as or differentfrom the proposed target neighbor cell identified in the PCCN message630 (e.g., to reduce service interruption), etc. Returning to FIG. 2, inresponse to receiving the PCCC message 662, the MS 125 suspends the TBFwith cell 1 and performs autonomous reselection to cell 2 (block 664).As shown in FIG. 2, the NACC processing time from initially sending thePCCN message 630 through receipt of the PCCC message 662 isapproximately 80 milliseconds (ms). The message sequence diagram 600then ends.

Given the context provided by the prior art cell reselection operationillustrated in FIG. 2, the example techniques to monitor channels forneighbor cell information disclosed herein and their potential benefitsare now described. For example, in the message sequence diagram 600 ofFIG. 2, cell 1 sends all of the PNCD messages 644, 646 and 652 to the MS125 to convey complete neighbor cell information for cell 2 (e.g., inthe form of all of the SI messages SI-1, SI-3 and SI-13) regardless ofwhether the MS 125 already has this neighbor cell information. Forexample, if less than a certain time period, such as thirty (30)seconds, has elapsed since some or all of the system messages 612-616were received, the MS 125 may still have some or all of the SI messagesSI-1, SI-3 and SI-13 for cell 2 stored in memory. In such an example,some or all of the PNCD messages 644, 646 and 652 containing these sameSI messages may be redundant and, thus, unnecessary. Additionally oralternatively, the example techniques to monitor channels for neighborcell information described herein can be used by the MS 125 to obtainneighbor cell information for cell 2, thereby also making some or all ofthe PNCD messages 644, 646 and 652 containing this same neighbor cellinformation redundant and, thus, unnecessary. By taking advantage ofneighbor cell information already stored in the MS 125, some or all ofthe PNCD messages 644, 646 and 652 can be omitted, resulting in apotential saving of radio resources or reduction in the delay before amobility procedure can be completed, or both.

With the foregoing in mind, a message sequence diagram 700 illustratingan example technique to monitor channels for neighbor cell informationand an example technique to avoid transmission of redundant neighborcell information implemented according to the methods and apparatusdescribed herein is provided in FIG. 3. For clarity, like elements inFIGS. 1-3 are labeled with the same reference numerals. Detaileddescriptions of these like elements are provided above in connectionwith FIG. 2. Also, in FIG. 3, as in the preceding figure, cell 1, asimplemented by the BSC 105 and the BTS 110, is represented by block 205,and cell 2, as implemented by the BSC 105 and the BTS 115, isrepresented by block 605. FIG. 3 further includes the MS 125 and MS 130of the GERAN system 100 of FIG. 1.

Turning to FIG. 3, operation of the message sequence diagram 700 from MS125 being in idle mode and camped on cell 2 (represented by the hollowdirected line 610), to reselecting to and camping on cell 1 (representedby the hollow directed lines 618 and 620), then to establishing the UL(as well as DL) TBF (represented by the hollow directed line 622), andthen exchanging UL RLC/MAC data blocks 624-626 is substantially similarto the example message sequence diagram 600 of FIG. 2. Accordingly, thisportion of the message sequence diagram 700 is not repeated for brevity.

Unlike the prior art operation illustrated in FIG. 2, the messagesequence diagram 700 illustrates an example operation of the MS 125 tomonitor channels for neighbor cell information as disclosed herein. Assuch, in addition to establishing the UL TBF (represented by the hollowdirected line 622) and exchanging UL RLC/MAC data blocks 624-626, the MS125 is also able to monitor channels conveying neighbor cell informationto other MSs operating in the GERAN system 100. For example, in theillustrated example and unlike the prior art, the MS 125 is configuredto monitor PACCH channels, such as the PACCH 140, for non-distributionmessages, such as PNCD messages, conveying neighbor cell information toother MSs, such as the MS 130. Such configuration may be implicit inwhich the MS 125 automatically monitors the PACCH 140 (e.g., wheneverthe PACCH 140 is available, based on MS operating mode, etc.), orexplicit in which the network may send one or more messages to authorizethe MS 125 to monitor the PACCH 140.

For example, in the message sequence diagram 700, the MS 130 is alsocamped on cell 1 and then initiates cell reselection identifying cell 2as the proposed target cell. This triggers a NACC procedure between theMS 130 and cell 2 (represented by the directed line 710). Because NACCis triggered, cell 1 begins sending neighbor cell system information forcell 2 to the MS 130. In the illustrated example, cell 1 sends threePNCD messages 712, 714 and 716 via the PACCH 140 to the MS 130 to conveySI messages SI-1, SI-3 and SI-13, respectively, for cell 2 (the proposedtarget cell identified by the MS 130 when the NACC procedure wastriggered). Although the PNCD messages 712, 714 and 716 arenon-distribution messages addressed specifically to the MS 130 (e.g.,using a TFI corresponding to a TBF assigned to the MS 130), the GERANsystem 100 permits monitoring of non-distribution messages containingneighbor cell information. Accordingly, the MS 125 in the illustratedexample is configured to monitor the PACCH channel 140 for PNCD messagessent to itself or to other mobile stations (e.g., corresponding to PNCDmessages having TFI(s) different than the TFI(s) identifying TBF(s)assigned to the MS 125), such as the PNCD messages 712, 714 and 716 sentvia the PACCH 140 to the MS 130. By monitoring the PACCH 140 andreceiving some or all of the PNCD messages 712, 714 and 716, the MS 125is able to obtain and store neighbor cell system information for cell 2for subsequent use (e.g., such as during subsequent mobility procedures,call re-establishment, etc.).

In the message sequence diagram 700, after the PNCD messages 712, 714and 716 are sent by cell 1 and monitored by the MS 125, the MS 125triggers autonomous reselection in response to detecting one or moreautonomous reselection criteria (block 628). After triggering autonomousreselection at block 628, the MS 125 sends a PCCN message 718 to cell 1(its serving cell) to indicate that autonomous reselection is possibleand to identify cell 2 as the proposed target neighbor cell. However,unlike in the prior art operation illustrated in FIG. 2, here the GERANsystem 100 supports the example techniques to avoid sending redundantneighbor cell information described herein. As such, in addition toidentifying cell 2 as the proposed target cell, the MS 125 is alsoconfigured to indicate to the network via the PCCN message 718 what, ifany, neighbor cell information for cell 2 (the proposed target cell),and possibly other cells, is already stored and valid in the MS 125. Forexample, in the message sequence diagram 700, the MS 125 indicates viathe PCCN message 718 that MS 125 is storing valid SI messages SI-1 andSI-3 for target neighbor cell 2. In the illustrated example, the MS 125may have obtained the stored SI messages SI-1 and SI-3 by monitoring thePACCH channel 140 and receiving, storing and processing the PNCDmessages 712 and 714 sent by cell 1 and addressed to MS 130.Additionally or alternatively, the MS 125 may still be storing the SImessages SI-1 and SI-3 obtained by receiving the system informationmessages 612 and 614 broadcast by cell 2, if a certain time period, suchas thirty (30) seconds, during which system information can be storedbefore being discarded has not yet elapsed.

As in FIG. 2, in the illustrated example of FIG. 3, two UL slots and twoDL slots have been allocated for communications between the MS 125 andcell 1. Thus, after sending the PCCN message 718, the MS 125 and cell 1exchange UL and DL RLC/MAC data blocks 634-642 as shown. Then, cell 1 isable to begin sending PNCD messages containing neighbor cell informationfor cell 2 to the MS 125 in the next radio block period after receivingthe PCCN message 718. However, unlike in the prior art operationillustrated in FIG. 2, here cell 1 is able to avoid sending redundantneighbor cell information to the MS 125 by omitting to send (or, inother words, not sending) PNCD messages containing valid neighbor cellinformation known to be stored in the MS 125. For example, in themessage sequence diagram 700, cell 1 receives the validity indicationsincluded in the PCCN message 718 indicating that the MS 125 already isstoring valid SI-1 and SI-3 messages for cell 2. Thus, the network candetermine that sending the SI-1 and SI-3 messages to the MS 125 inresponse to the PCCN message 718 would be redundant and, thus,unnecessary for supporting the NACC procedure. Accordingly, in themessage sequence diagram 700, cell 1 sends the PNCD message 652containing the SI message SI-13 for cell 2 to the MS 125 because the MS125 indicated (implicitly) via the PCCN message 718 that it did not havea valid SI-13 message stored for cell 2. But, cell 1 is able to omitsending the PNCD messages 644 and 646 used to convey SI messages SI-1and SI-3, respectively, for cell 2 in the message sequence diagram 600because cell 1 knows that these SI messages are already stored in the MS125 and, thus, sending them again would be redundant. Cell 1 then usesthe other allocated DL slot to send another DL RLC/MAC data block 654 tothe MS 125.

In the next radio block period, the MS 125 is able to send UL RLC/MACdata blocks 648-650 in its two allocated UL slots. In theassigned/allocated DL slots, cell 1 sends the DL RLC/MAC data block 660followed by the PCCC message 662. As described above, the PCCC message662 indicates that the MS 125 can perform reselection to the proposedtarget cell (e.g., cell 2 in the illustrated example). In response toreceiving the PCCC message 662, the MS 125 suspends the TBF with cell 1and performs autonomous reselection to cell 2 (block 664). The examplemessage sequence diagram 700 then ends.

As shown in FIG. 3, the NACC processing time from initially sending thePCCN message 718 through receipt of the PCCC message 662 is 60 ms. Incontrast, the prior art example of FIG. 2 required 80 ms. from sendingof the PCCN message 630 through receipt of the PCCC message 662.Therefore, the example techniques described herein enable cellreselection to be performed and concluded faster, in at least in somescenarios. Additionally, fewer radio resources (e.g., two less radioblocks of bandwidth) were consumed by the example of FIG. 3, relative tothe prior art example of FIG. 2, to complete the cell reselectionprocedure.

To provide further context for the example techniques to monitorchannels for neighbor cell information and the example techniques toavoid transmission of redundant neighbor cell information describedherein, an example prior art CRE procedure that could be implemented inthe GERAN system 100 is illustrated in the message sequence diagram 800of FIG. 4. In FIG. 4, as in the preceding figures, cell 1, asimplemented by the BSC 105 and the BTS 110, is represented by block 205,and cell 2, as implemented by the BSC 105 and the BTS 115, isrepresented by block 605. FIG. 4 further includes the MS 125 of theGERAN system 100 of FIG. 1.

As mentioned above, the CRE procedure allows an MS in a GERAN system tore-establish an existing call after experiencing a radio link failurewithout user intervention. In a conventional implementation, the MSperforming the CRE procedure is to perform acquisition of systeminformation of a target neighbor cell (if the system information is notalready stored) before initiating call re-establishment signaling tore-establish the call with the target neighbor cell. Turning to FIG. 4,the message sequence diagram 800 begins with a dual transfer mode (DTM)call being established between the MS 125 and cell 1 (represented by thehollow directed line 810). A DTM call is a call supporting both packetswitched traffic and circuit switched traffic (e.g., such as circuitswitched voice communications). After the DTM call is established, theMS 125 detects valid slow associated control channel (SACCH) messages812-814 broadcast by cell 1. By detecting the valid SACCH messages812-814 during the DTM call, the MS 125 is able to determine that itstill has a good radio link with cell 1.

Next, the MS 130 detects a bad SACCH message 816 (or fails to detect anySACCH message) corresponding to a potential radio link failure. In theillustrated example, the MS 125 continues to detect bad SACCH messagesuntil a bad SACCH message 820 is detected. Detection of the bad SACCHmessage 820 corresponds to determination that the radio link has failedand also interruption of the voice session supported by the DTM(represented by the hollow directed line 818), although prior gaps in orcorruption of the audio, or both, may occur before the voice session iscompletely interrupted. Thus, at block 822 the MS 125, having determinedthat a radio link failure has occurred, triggers the CRE procedure toattempt to re-establish the call.

Next, as part of the CRE procedure, the MS 125 begins receiving andacquiring system information for neighbor cells. For example, in themessage sequence diagram 800, the MS 125 receives system informationmessages 824-832 broadcast by cell 2, which is a neighbor cell of cell1. In addition, the MS 125 may receive and acquire system informationfor the serving cell (cell 1). After acquiring sufficient systeminformation messages (e.g., such as the SI-1, SI-3 and SI-13) for cell2, and determining that cell 2 is preferred over other neighbor cellssupporting CRE, the MS 125 initiates call re-establishment signaling bysending a channel request message 834 to cell 2 via a random accesschannel (RACH). The channel request message 834 requestsre-establishment of at least the voice component of the DTM callpreviously served by cell 1. Subsequent CRE signaling includes animmediate assignment message 836 sent from cell 2 to the MS 125, aconnection management (CM) re-establishment request message 838 sentfrom the MS 125 to cell 2, and a CM service accept message 840 sent fromcell 2 to the MS 125. After the CM service accept message 840 isreceived by the MS 125, the voice call is successfully re-established(represented by the hollow directed line 842) and the associated voicesession is no longer interrupted.

Successful call re-establishment, such as that illustrated in FIG. 4,allows the MS 125 to re-establish a traffic channel and continue a callwithout user intervention (e.g., without the user manually re-dialingthe call and waiting for the called party to answer). However, thenetwork typically allots a limited (possibly configurable) time duringwhich call re-establishment may be attempted, after which the call isdropped. Thus, reducing the time expended from the MS 125 detecting aradio link failure to sending the channel request message 834 to a newtarget cell (e.g., cell 2) improves the likelihood that callre-establishment will complete successfully during the allotted time. Asshown in FIG. 4, receiving and processing the system informationmessages 824-832 for the target neighbor cell is a significant portionof this time. Reducing the time spent obtaining neighbor cell systeminformation for target neighbor cells, therefore, can improve callre-establishment reliability, in at least some scenarios. Additionally,because the voice session is interrupted while the call is beingre-established, reducing the time to re-establish the call can improveuser-perceived audio quality by shortening the perceived gaps in audiowhile the call is being re-established, in at least some scenarios.

With the foregoing in mind, a message sequence diagram 900 illustratingan example technique to monitor channels for neighbor cell informationthat can be used in a CRE procedure is provided in FIG. 5. For clarity,like elements in FIGS. 1, 4 and 5 are labeled with the same referencenumerals. Detailed descriptions of these like elements are providedabove in connection with FIG. 4. Also, in FIG. 5, as in the precedingfigures, cell 1, as implemented by the BSC 105 and the BTS 110, isrepresented by block 205, and cell 2, as implemented by the BSC 105 andthe BTS 115, is represented by block 605. FIG. 5 further includes the MS125 and MS 130 of the GERAN system 100 of FIG. 1.

Turning to FIG. 5, the message sequence diagram 900 also begins with theDTM call being established between the MS 125 and cell 1 (represented bythe hollow directed line 810). Additionally, a packet transfer mode forexchanging packet-switched traffic is established between the MS 130 andcell 1 (represented by the hollow directed line 910). Next, the MS 125detects valid SACCH messages 910-918 broadcast by cell 1 during the DTMcall. As described above, by detecting the valid SACCH messages 910-918during the DTM call, the MS 125 is able to determine that it still has agood radio link with cell 1.

While the MS 125 is detecting the valid SACCH messages 910-918 duringthe DTM call, the MS 130 is exchanging packet transfer mode messageswith cell 1, such as any non-PNCD message 920 conveyed via the PACCH140. Then, the MS 130 initiates cell reselection identifying cell 2 asthe proposed target cell. This triggers an NACC procedure between the MS130 and cell 2 (represented by the directed line 922). Because NACC istriggered, cell 1 begins sending neighbor cell system information forcell 2 to the MS 130. In the illustrated example, cell 1 sends threePNCD messages 924, 926 and 928 via the PACCH 140 to the MS 130 to conveySI messages SI-1, SI-3 and SI-13, respectively, for cell 2 (the proposedtarget cell identified by the MS 130 when the NACC procedure wastriggered). Although the PNCD messages 924, 926 and 928 arenon-distribution messages addressed specifically to the MS 130 (e.g.,using a TFI assigned to the MS 130), the GERAN system 100 permitsmonitoring of non-distribution messages containing neighbor cellinformation. Accordingly, the MS 125 in the illustrated example isconfigured to monitor the PACCH channel 140 for PNCD messages sent toitself or to other mobile stations (e.g., corresponding to PNCD messageshaving TFI(s) different than the TFI(s) identifying TBF(s) assigned tothe MS 125), such as the PNCD messages 924, 926 and 928 sent via thePACCH 140 to the MS 130. By monitoring the PACCH 140 and receiving thePNCD messages 924, 926 and 928, the MS 125 is able to obtain and storeneighbor cell system information for cell 2 that can be used duringsubsequent mobility procedures.

Next, operation of the message sequence diagram 900 continues as in theprior art example of FIG. 4 from the MS 125 detecting of the good SACCH812 through the MS 125 determining a radio link failure has occurredand, thus, triggering the CRE procedure to re-establish the call (block822). However, unlike the prior art example of FIG. 4, in theillustrated example of FIG. 5, the MS 125 has already obtained theneighbor cell information for cell 2 by monitoring the PACCH 140 andreceiving, storing and processing the system information included in thePNCD messages 924-928 sent by cell 1 to the other mobile station 130.Thus, in the message sequence diagram 900 in which the MS 125 isconfigured to monitor channels for neighbor cell information asdescribed herein, the MS 125 can forego expending the time and resourcesto receive and process the system information messages 824-832 broadcastby cell 2 in the prior art example of FIG. 4. Instead, the MS 125 usesthe system information obtained from the PNCD messages 924-928 sent bycell 1 to the other mobile station 130 to initiate call re-establishmentsignaling (represented by the dashed box 930). Then, callre-establishment signaling of messages 834-840 continues as in theexample of FIG. 4, culminating in the voice call being successfullyre-established (represented by the hollow directed line 842) and theassociated voice session no longer being interrupted. As depicted inFIG. 5, employing monitoring of channels for neighbor cell informationas described herein can avoid having the MS 125 expend valuable time andresources to acquire neighbor cell information, potentially improvingthe likelihood of successful call re-establishment, as well asuser-perceived audio quality in the form of reduced audio gaps duringcall re-establishment.

A block diagram of an example implementation of the MS 125 of FIG. 1 isillustrated in FIG. 6. The example implementation illustrated in FIG. 6could also be used to implement either or both of the MSs 130 and 135 ofFIG. 1, but for brevity and clarity, FIG. 6 is described from theperspective of implementing the MS 125 of FIG. 1. Turning to FIG. 6, theillustrated example implementation of the MS 125 includes a channelmonitor 1005 to monitor one or more communication channels for messagescontaining neighbor cell information. For example, when the MS 125 isoperating in a packet switched (PS) or DTM mode, the MS 125 isconfigured to receive messages over a channel, such as the PACCH 140.The PACCH channel 140 is shared (e.g., multiplexed) with other MSsoperating in PS or DTM modes, such as the MSs 130 and 135. In aconventional implementation, the MS 125 is to retain (e.g., store forsubsequent use) only that non-distribution information contained inmessages on the PACCH 140 that contain a TFI assigned to the MS 125 and,thus, is addressed to the MS 125. The MS 125 in such a conventionalimplementation is to discard non-distribution information contained inPACCH message blocks containing TFIs assigned to other MSs and, thus,that are addressed to these other MSs.

However, in the implementation of FIG. 6, the channel monitor 1005 isconfigured to not immediately discard the contents of PACCH or otherchannel message blocks not addressed to the MS 125 (e.g., not containinga TFI assigned to the MS 125). Instead, the channel monitor 1005examines the messages sent via the channel (e.g., PACCH 140) for messageblocks containing neighbor cell information regardless of whether themessage blocks are addressed to the MS 125 or another MS. For example,in a scenario in which cell 1 of the GERAN system 100 supports NACC orNC2, or both, the cell will send PNCD messages containing neighbor cellsystem information to MSs (e.g., such as the MSs 130, 135) undergoingmobility procedures, such as cell reselection, PS handover, etc. Usingthe channel monitor 1005, the MS 125 examines the PACCH 140 for PNCDmessages addressed to any MS (e.g., having any TFI) and is able toreceive and retain (e.g., store for subsequent use) the neighbor cellsystem information contained in these PNCD messages sent to other MSs(e.g., such as the MSs 130, 135).

The MS 125 of FIG. 6 also includes a message decoder 1010 to decode themessages received by the channel monitor. In an example implementation,the message decoder 1010 implements a PNCD message decoder and isconfigured to decode PNCD messages to obtain the neighbor cell systeminformation contained in these messages. For example, PNCD messages areused to convey neighbor cell system information in the form of one ormore SI messages, such as the SI messages SI-1, SI-3, and SI-13 messagesdiscussed above. The message decoder 1010 decodes the SI messagesincluded in the PNCD messages received by the channel monitor 1005. Themessage decoder 1010 also associates the decoded SI messages with aparticular neighbor cell using identification information contained inthe decoded PNCD message or in other messages related to theprovisioning of neighbor cell information (e.g., such as PCCC, PCCO andPSHO messages) that are received by the channel monitor 1005. Theresulting decoded neighbor cell system information (e.g., decoded SImessages) and the associations of the decoded information withparticular neighbor cells are stored in a memory unit 1015.

In some operating scenarios, the message decoder 1010 is able to decodea complete SI message from a single PNCD message. However, in otheroperating scenarios, the message decoder 1010 decodes SI messages bycombining system information contained in multiple PNCD messages sent ina given radio block period or across multiple radio block periods.Example operation of the message decoder 1010 to decode SI messages fromreceived PNCD messages and to associate the decoded SI messages with aparticular neighbor cell is illustrated in FIGS. 7-8.

For example, FIG. 7 depicts four PNCD messages 1105, 1110, 1115 and 1120sent by cell 1 to an MS other than the MS 125 during a given radio blockperiod. The PNCD messages 1105-1120 are used to convey SI messages SI-1,SI-3 and SI-13 for a particular neighbor cell. Because each SI messageis larger than the payload supported by any one of the PNCD messages1105-1120, each SI message is split over two adjacent PNCD messages1105-1120 as shown. In the illustrated example, the message decoder 1010uses temporary identifiers included in the received PNCD messages1105-1120 to combine information contained in the multiple PNCD messages1105-1120 to decode the SI messages SI-1, SI-3 and SI-13 and associatethe decoded SI messages with a particular neighbor cell.

For example, the message decoder 1010 determines that each of the PNCDmessages 1105-1120 is addressed to the same MS, for example, because theTFI in each of these PNCD messages is the same (e.g., TFI=5 in theillustrated example) and the messages were received on the same timeslotindex (e.g., for BTTI mode) or pair of timeslot indices (e.g., for RTTImode). Alternatively, since the probability of two mobiles beingassigned a TBF using the same TFI (but using non-overlapping timeslots)and receiving PNCD messages at the same time is very low, the MS maycombine PNCD messages with the same TFI but received on differenttimeslots or timeslot pairs. Thus, the TFI is a first temporaryidentifier included in the received PNCD messages 1105-1120 that,possibly in conjunction with the received timeslot index or pair oftimeslot indices, can be used to determine which received PNCD messagescan be grouped together as being addressed to the same MS. The messagedecoder 1010 further determines that the SI messages included in thePNCD messages 1105-1120 contain neighbor cell system information for thesame neighbor cell because the CONTAINER_ID included in each of thesePNCD messages is the same (e.g., CONTAINER_ID=4 in the illustratedexample). The CONTAINER_ID is a second temporary identifier included inthe received PNCD messages 1105-1120 to group neighbor cell informationfor a particular neighbor cell. In at least some implementations, theCONTAINER_ID is used instead of explicitly identifying the neighbor cellbecause the CONTAINER_ID is smaller than the complete identificationinformation for a cell. By combining neighbor cell system informationreceived over the multiple PNCD messages according to TFI (as well astimeslot index or pair of timeslot indices in some examples) andCONTAINER_ID, and in the order specified by the CONTAINER_INDEXparameter, the message decoder 1010 can group and decode SI messages fora particular neighbor cell. In order to reduce the risk of combiningPNCD messages that were not addressed to the same mobile, or do notrelate to the same cell, but nevertheless have the same TFI (or same TFIand same CONTAINER_ID) values (e.g., because the TFI was reassignedand/or the PNCD messages were received in different timeslots/PDCHs),the message decoder 1010 may apply a time restriction on the length of atime window within which such messages may be received and combined.

Additionally, in some example implementations, the message decoder 1010is configured to monitor for PACCH messages sent using a differenttransmission time interval (TTI) from that used for downlink messagesaddressed to the MS 125. For example, in the downlink, the network maysend message blocks to a first MS using a first TTI (e.g. such as a BTTIwherein one block is transmitted over 20 ms) and message blocks to asecond MS using a different TTI (e.g. such as an RTTI wherein one blockis transmitted using two timeslots over 10 ms). Conventionally, an MSmonitors and decodes message blocks assuming the TTI which is applicableto its TBF(s). However, in at least some example implementations, the MS125 implementing the message decoder 1010 could attempt to decodemessage blocks using a different TTI than the TTI applicable to itsTBF(s).

When the message decoder 1010 uses temporary identifiers to associatedecoded SI messages with a particular neighbor cell, the message decoder1010 uses information from other messages received by the channelmonitor 1005 to identify the particular neighbor cell corresponding tothe decoded neighbor cell information. For example, FIG. 7 depictsanother message 1125 received by the channel monitor 1005, such asanother PNCD message or a PCCC, PCCO or PSHO message. The messagedecoder 1010 decodes the message 1125 and determines that the TFI andCONTAINER_ID included in the decoded message 1125 match the TFIs andCONTAINER_IDs included in the decoded PNCD messages 1105-1120. Themessage decoder 1010 further determines that the message 1125 includescell identification information in the form of a base stationidentification code (BSIC=2 in the illustrated example) and an absoluteradio frequency channel number (ARFCN=25 in the illustrated example).Thus, by correlating the TFIs and CONTAINER_IDs included in the decodedPNCD messages 1105-1120 and the decoded message 1125, the messagedecoder is able to determine that the SI messages decoded from the PNCDmessages 1105-1120 are associated with the neighbor cell identified bythe BSIC and ARFCN included in the message 1125. In example scenario inwhich complete cell identification information (e.g., such as BSICs andARFCNs) are included in the PNCD messages containing neighbor cellsystem information, the message decoder 1010 can associate decoded SImessages with a particular neighbor cell directly without using thetemporary identifiers described above.

FIG. 8 depicts a scenario in which neighbor cell system informationcontained in PNCD messages sent over multiple radio block periods iscombined to decode SI messages for a particular neighbor cell. In theillustrated example, PNCD messages 1205, 1210, 1215 and 1220 are sentfirst during one or more radio block periods 1225. In the illustratedexample, the message decoder 1010 decodes the PNCD messages 1205, 1210and 1220 addressed to another MS assigned TFI=5, but does not decode thePNCD message 1215 (e.g., due to a scheduling conflict). Because themessage decoder 1010 is unable to decode the PNCD message 1215, themessage decoder 1010 is also unable to decode the SI-3 and SI-13messages sent in the radio block period 1225. Thus, during the radioblock period 1225, the message decoder 1010 decodes only the SI-1message conveyed via the PNCD messages 1205 and 1210 that weresuccessfully decoded.

However, in the illustrated example, PNCD messages 1235, 1240, 1245 and1250 conveying these same SI messages for the same neighbor cell (e.g.,represented by BSIC=2 and ARFCN=25) are sent again during subsequentradio block period(s) 1255. Again, the message decoder 1010 is unable todecode one of the received PNCD messages, the PNCD message 1250 (e.g.,due to a scheduling conflict), but is able to decode the other PNCDmessages 1235-1245. Because the network also varies the ordering of theSI messages across radio block periods as shown in the example of FIG.8, the message decoder 101 is able to decode the SI-3 and SI-13 messagesfrom the PNCD messages 1235-1245 received during the radio block period1255 and combine these messages with the SI-1 message decoded from thePNCD messages 1205-1210 received during the radio block period 1225 toobtain complete information for this neighbor cell (e.g., represented byBSIC=2 and ARFCN=25).

Returning to FIG. 6, in at least some example implementations, thechannel monitor 1005 and the message decoder 1010 are configured toreceive and decode distribution (e.g., broadcast) messages containingneighbor cell system information broadcast via the channel to some orall MSs. For example, cell 1 in the GERAN system 100 could be configuredto broadcast packet neighbor cell system information distributionmessages each containing all or part of an SI message for a particularneighbor cell and that can be received and decoded by any MS configuredto receive messages via the PACCH 140. Such distribution messagescontaining neighbor cell system information could be broadcast insteadof non-distribution PNCD whenever a particular MS is involved in certainmobility procedures, such as NACC or NC2 procedures. Thus, in such anexample implementation, whenever any MS is involved in these certainmobility procedures, all MSs configured to receive messages via thePACCH 140 can benefit from the neighbor cell system information beingsent by the network.

As shown and described in FIGS. 6-8, as well as the preceding figures,the channel monitor 1005 and the message decoder 1010 can be used toimplement monitoring of channels for neighbor cell information in the MS125 while the MS 125 is operating in PS mode, DTM mode, or also idlemode. The neighbor cell system information obtained by the channelmonitor 1005 and the message decoder 1010 can be used by a neighbor cellaccess processor 1020 included in the MS 125 in idle mode or PS mode to,for example, perform cell reselection using stored neighbor cellinformation rather than, or in addition to, neighbor cell informationprovided by the network, thereby potentially resulting in faster cellreselection. In dedicated mode or DTM mode, the neighbor cell accessprocessor 1020 can use stored neighbor cell information to expedite CREbecause the MS 125 may not have to wait to receive SI messages broadcastby the target cell before initiating call reestablishment signaling.

Referring again to FIG. 6, the MS 125 of the illustrated example alsoincludes a system information validity processor 1025 to set one or moreSI validity indications representing whether the MS 125 has valid systeminformation (e.g., SI messages) stored for one or more neighbor cells.In the illustrated example, the system information validity processor1025 sets the SI validity indication(s) when undergoing certain mobilityprocedures, such as cell reselection with NACC enabled, measurementreporting in NC2 mode, etc. In an example implementation, an SI validityindication is implemented by a bitmap or set of bits associated with aparticular neighbor cell, with each bit associated with a particular SImessage for that neighbor cell. For example, an SI validity indicationfor cell 2 could be implemented as a bitmap having three (3) bits, witha first bit associated with the SI-1 message for cell 2, a second bitassociated with the SI-3 message for cell 2, and a third bit associatedwith the SI-13 message for cell 2. Alternatively, the SI validityindication could be implemented as a bitmap in which each bit representsa particular neighbor cell and indicates whether all necessary (or aparticular set or subset) SI messages for the neighbor cell are storedin the MS 125 (e.g., similar to an all-or-nothing indication). Forexample, the SI validity indication could be implemented as a bitmaphaving six (6) bits representative of 6 neighbor cells, with a first bitindicating whether the SI-1, SI-3 and SI-13 messages are all stored forcell 1, a second bit indicating whether the SI-1, SI-3 and SI-13messages are all stored for cell 2, a third bit indicating whether theSI-1, SI-3 and SI-13 messages are all stored for cell 3, and so on.Alternatively, the SI validity indication could indicate the time sincethe associated SI was most recently received. For example, the SIvalidity indication could indicate whether an SI message was mostrecently received within the last 30 seconds (s), within the last hour,within the last 12 hours, or has not been received within the last 12hours. In this latter example, the network can determine whether to sendSI message(s) to the MS 125 based on either or both of (i) when the SImessage(s) were received by the MS 125 as indicated by the reported SIvalidity indication(s), and (ii) whether the contents of the SImessage(s) changed since being received by the MS 125.

In the illustrated example, the system information validity processor1025 sets a bit in the SI validity indication bitmap to indicate thatthe corresponding SI message for the corresponding neighbor cell isstored (and valid) at the MS 125. The system information validityprocessor 1025 clears bit(s) for corresponding SI message(s) that arenot stored (and, thus, not valid) at the MS 125. In an exampleimplementation, an SI message for neighbor cells can be stored in thememory unit 1015 of the MS 125 for a certain period of time (e.g., 30sec.) after which the SI message is to be discarded. The neighbor cellsystem information reported via the SI validity indication(s) set by thesystem information validity processor 1025 may be obtained in anyappropriate manner, such as via monitoring channels for neighbor cellinformation, receiving SI messages broadcast via one or more neighborcells, etc.

The MS 125 of FIG. 6 also includes a message encoder 1030 to encode theSI validity indication(s) set by the system information validityprocessor 1025 into one or more messages to be sent to the network(e.g., sent to cell 1 in the GERAN system 100). For example, withreference to FIG. 3, when the MS 125 is undergoing cell reselection withCCN enabled, the message encoder 1030 includes the SI validityindication(s) set by the system information validity processor 1025 inthe PCCN message 718 sent to cell 1 (e.g., such as in a bit field ormeasurement report included in the PCCN message 718). In this way, theSI validity indication(s) included by the message encoder 1030 in thePCCN message 718 indicate what, if any, neighbor cell system informationis stored (and valid) at the MS 125 and, thus, is already available forthe cell reselection procedure. Additionally or alternatively, when theMS 125 is operating in NC2 mode, the message encoder 1030 includes theSI validity indication(s) set by the system information validityprocessor 1025 in one or more measurement reports sent by the MS 125 forcell reselection. Again, these SI validity indication(s) indicate what,if any, neighbor cell system information is stored (and valid) at the MS125 and, thus, does not need to be provided by the network prior toreselecting to the target neighbor cell.

Thus, as shown and described in FIG. 6, as well as the precedingfigures, the system information validity processor 1025 and the messageencoder 1030 can be used to implement avoidance of transmission ofredundant neighbor cell information in the MS 125 while the MS 125 isoperating in PS mode, DTM mode, or also idle mode.

While an example manner of implementing the example MS 125 of FIG. 1 hasbeen illustrated in FIG. 6, one or more of the elements, processesand/or devices illustrated in FIG. 6 may be combined, divided,re-arranged, omitted, eliminated and/or implemented in any other way.Further, the example channel monitor 1005, the example message decoder1010, the example memory unit 1015, the example neighbor cell accessprocessor 1020, the example system information validity processor 1025,the example message encoder 1030 and/or, more generally, the example MS125 of FIG. 6 may be implemented by hardware, software, firmware and/orany combination of hardware, software and/or firmware. Thus, forexample, any of the example channel monitor 1005, the example messagedecoder 1010, the example memory unit 1015, the example neighbor cellaccess processor 1020, the example system information validity processor1025, the example message encoder 1030 and/or, more generally, theexample MS 125 could be implemented by one or more circuit(s),programmable processor(s), application specific integrated circuit(s)(ASIC(s)), programmable logic device(s) (PLD(s)) and/or fieldprogrammable logic device(s) (FPLD(s)), etc. When any of the appendedclaims are read to cover a purely software and/or firmwareimplementation, at least one of the example MS 125, the example channelmonitor 1005, the example message decoder 1010, the example memory unit1015, the example neighbor cell access processor 1020, the examplesystem information validity processor 1025 and/or the example messageencoder 1030 are hereby expressly defined to include a tangible mediumsuch as a memory, digital versatile disk (DVD), compact disk (CD), etc.,storing such software and/or firmware. Further still, the example MS 125of FIG. 6 may include one or more elements, processes and/or devices inaddition to, or instead of, those illustrated in FIG. 6, and/or mayinclude more than one of any or all of the illustrated elements,processes and devices.

A block diagram of an example implementation of the BSC 105 of FIG. 1(possibly in conjunction with a BTS, such as the BTS 110) is illustratedin FIG. 9. Although described from the perspective of implementing cell1 of FIG. 1, the example implementation illustrated in FIG. 9 could alsobe used to implement either or both of cells 2 and 3 of FIG. 1. Turningto FIG. 9, the illustrated example implementation of the BSC 105includes a system information validity decoder 1305 to decode SIvalidity indications included in messages received from MSs, such as theMS 125. The BSC 105 may be implicitly configured to support receiving SIvalidity indications, or may be configured to broadcast a messageindicating whether receipt of SI validity indications is supported. Forexample, if NACC is supported, the system information validity decoder1305 decodes SI validity indications included in PCCN messages sent bythe MS 125 during cell reselection. Additionally or alternatively, ifNC2 mode is supported, the system information validity decoder 1305decodes SI validity indications included in measurement reports providedby the MS 125.

In conventional implementations, the BSC 105 and, more generally, thenetwork are unaware of what, if any, neighbor cell system information isstored at the MS 125. Unlike conventional implementations, the systeminformation validity decoder 1305 decodes SI validity indicationsprovided by the MS 125 to determine what, if any, valid neighbor cellsystem information is already stored at the MS 125. The BSC 105 can usethese indications to determine whether and what neighbor cell systeminformation to schedule for subsequent sending to the MS 125. Asdescribed above, in the illustrated example of FIG. 7, the SI validityindication is implemented by a bitmap or set of bits associated with aparticular neighbor cell, with each bit associated with a particular SImessage for that neighbor cell, or with each bit in the bitmapassociated with a respective neighbor cell and indicating whether allneeded SI messages (e.g., such as a particular set or subset of SImessages) are stored for that neighbor cell, or with one or more bitsassociated with a respective neighbor cell and indicating the time sincethe most recent reception of one or more respective SI messages for thatneighbor cell. In such an example, the system information validitydecoder 1305 decodes each bit in a received SI validity indicationbitmap to determine what, if any, valid SI messages are stored at the MS125 for the neighbor cell(s) corresponding to the decoded SI validityindication bitmap.

The BSC 105 of FIG. 9 also includes a message scheduler 1310 to schedulesubsequent sending of messages containing neighbor cell informationbased on the SI validity indications decoded by the system informationvalidity decoder 1305. For example, with reference to FIG. 3, inresponse to receiving an SI validity indication in the PCCN message 718sent by the MS 125 during cell reselection with NACC enabled, themessage scheduler 1310 determines what, if any, SI messages for thetarget cell (cell 2) are to be sent to the MS 125 via subsequent PNCDmessages. For example, in FIG. 3, the PCCN message 718 sent by the MS125 could include an SI validity indication bitmap for cell 2 with thebits corresponding to the SI-1 and SI-3 being set. Accordingly, themessage scheduler 1310 determines that valid SI-1 and SI-3 messages forcell 2 are already stored at the MS 125 and, thus, the message scheduler1310 determines to omit scheduling of PNCD messages to convey these sameSI messages again to the MS 125. Instead, the message scheduler 1310schedules only the PNCD message 652 containing the SI-13 message forcell 2 for subsequent sending to the MS 125.

Thus, as shown and described in FIG. 9, as well as the precedingfigures, the system information validity decoder 1305 and the messagescheduler 1310 can be used to implement avoidance of transmission ofredundant neighbor cell information in the BSC 105 (and, more generally,in the GERAN network 100).

While an example manner of implementing the example BSC 105 of FIG. 1has been illustrated in FIG. 9, one or more of the elements, processesand/or devices illustrated in FIG. 9 may be combined, divided,re-arranged, omitted, eliminated and/or implemented in any other way.Further, the example system information validity decoder 1305, theexample message scheduler 1310 and/or, more generally, the example BSC105 of FIG. 9 may be implemented by hardware, software, firmware and/orany combination of hardware, software and/or firmware. Thus, forexample, any of the example system information validity decoder 1305,the example message scheduler 1310 and/or, more generally, the exampleBSC 105 could be implemented by one or more circuit(s), programmableprocessor(s), application specific integrated circuit(s) (ASIC(s)),programmable logic device(s) (PLD(s)) and/or field programmable logicdevice(s) (FPLD(s)), etc. When any of the appended claims are read tocover a purely software and/or firmware implementation, at least one ofthe example BSC 105, the example system information validity decoder1305 and/or the example message scheduler 1310 are hereby expresslydefined to include a tangible medium such as a memory, digital versatiledisk (DVD), compact disk (CD), etc., storing such software and/orfirmware. Further still, the example the example BSC 105 of FIG. 9 mayinclude one or more elements, processes and/or devices in addition to,or instead of, those illustrated in FIG. 9, and/or may include more thanone of any or all of the illustrated elements, processes and devices.

Flowcharts representative of example processes that may be executed toimplement any, some or all of the example GERAN communication system100, the example BSC 105 (possibly in conjunction with one or more ofthe example BTSs 110-120), the example MSs 125-135, the cell 205, thecell 605, the example channel monitor 1005, the example message decoder1010, the example memory unit 1015, the example neighbor cell accessprocessor 1020, the example system information validity processor 1025,the example message encoder 1030, the example system informationvalidity decoder 1305 and the example message scheduler 1310 are shownin FIGS. 10-12.

In these examples, the process represented by each flowchart may beimplemented by one or more programs comprising machine readableinstructions for execution by: (a) a processor, such as the processor1712 shown in the example processing system 1700 discussed below inconnection with FIG. 13, (b) a controller, and/or (c) any other suitabledevice. The one or more programs may be embodied in software stored on atangible medium such as, for example, a flash memory, a CD-ROM, a floppydisk, a hard drive, a DVD, or a memory associated with the processor1712, but the entire program or programs and/or portions thereof couldalternatively be executed by a device other than the processor 1712and/or embodied in firmware or dedicated hardware (e.g., implemented byan application specific integrated circuit (ASIC), a programmable logicdevice (PLD), a field programmable logic device (FPLD), discrete logic,etc.). For example, any one, some or all of the example GERANcommunication system 100, the example BSC 105 (possibly in conjunctionwith one or more of the example BTSs 110-120), the example MSs 125-135,the cell 205, the cell 605, the example channel monitor 1005, theexample message decoder 1010, the example memory unit 1015, the exampleneighbor cell access processor 1020, the example system informationvalidity processor 1025, the example message encoder 1030, the examplesystem information validity decoder 1305 and the example messagescheduler 1310 could be implemented by any combination of software,hardware, and/or firmware. Also, some or all of the processesrepresented by the flowcharts of FIGS. 10-12 may be implementedmanually.

Further, although the example processes are described with reference tothe flowcharts illustrated in FIGS. 10-12, many other techniques forimplementing the example methods and apparatus described herein mayalternatively be used. For example, with reference to the flowchartsillustrated in FIGS. 10-12, the order of execution of the blocks may bechanged, and/or some of the blocks described may be changed, eliminated,combined and/or subdivided into multiple blocks.

An example process 1400 that may be performed to implement monitoring ofchannels for neighbor cell information in any, some or all of theexample MSs 125, 130 and 135 of FIG. 1 or 6, or both, is illustrated inFIG. 10. The process 1400 may be executed at predetermined intervals(e.g., such as based on a multiple of a radio block period), based on anoccurrence of a predetermined event (e.g., such as performance ofcertain mobility procedures), as a background process, etc., or anycombination thereof. Although the process 1400 could be used toimplement any of the MSs 125, 130 and 135, for brevity and clarity,operation of the process 1400 is described from the perspective ofimplementation in the MS 125 of FIG. 6 for operation in the GERAN system100 of FIG. 1.

With reference to the preceding figures, the process 1400 of FIG. 10begins at block 1405 at which the process 1400 determines whether the MS125 is operating in a mode supporting packet-switched data, such as apacket mode supporting packet data traffic, a dual transfer mode (DTM)supporting both packet data traffic and circuit data traffic, or even anidle mode. If the MS 125 is not operating in a mode supportingpacket-switched data (block 1405), the MS 125 then discards any expiredneighbor cell system information at block 1410. For example, the MS 125may be configured to delete any neighbor cell system information thathas been stored in the memory unit 1415 for more than a specified timeperiod (e.g., such as 30 sec.). Next, the process 1400 determines atblock 1415 whether monitoring of channels for neighbor cell informationis to continue (e.g., based on any appropriate criteria or input). Ifsuch monitoring is to continue (block 1415), the process 1400 returns toblock 1405 and blocks subsequent thereto to continue processing.However, if monitoring of channels for neighbor cell information is notto continue (block 1415), the process 1400 ends.

Returning to block 1405, if the MS 125 is operating in a mode supportingpacket-switched data (block 1405), the process 1400 then determines atblock 1420 whether the MS 125 is authorized to monitor the PACCH channel140 for neighbor cell information. For example, such authorization maybe implicit such that PACCH monitoring is always permitted, or thenetwork may send one or more messages to authorize the MS 125 to monitorthe PACCH 140. If PACCH monitoring is not authorized (block 1420),operation of the process 1400 proceeds to block 1410 and subsequentblocks, as described above.

However, if PACCH monitoring is authorized (block 1420), then at block1425 the channel monitor 1005 included in the MS 125 monitors the PACCH140 for non-distribution PNCD messages addressed to any MS configured toreceive message blocks via the PACCH channel 140 and that containneighbor cell system information. (In an example implementation, thechannel monitor 1005 may also monitor the PACCH 140 for distributionmessages containing neighbor cell system information broadcast to allMSs receiving message blocks via PACCH 140). If the channel monitor 1005determines that a received message is a PNCD message (block 1430), thenat block 1435 the message decoder 1010 included in the MS 125 decodesthe PNCD message received by the channel monitor 1005 regardless ofwhich MS was the intended recipient of the PNCD message. For example,with reference to FIG. 7, at block 1435 the message decoder 1010 decodesthe SI message, or portion thereof, included in the received PNCDmessage. Additionally, message decoder 1010 decodes the TFI andCONTAINER_ID (and/or other) temporary identifies included in thereceived PNCD message and that can be used to associate the decoded SImessage, or portion thereof, with a particular neighbor cell.

Next, at block 1440 the message decoder 1010 uses the decoded TFI andCONTAINER_ID temporary identifiers as illustrated in FIGS. 7-8 tocombine the SI message, or portion thereof, with stored SI message(s),or portion(s) thereof, having the same TFI and CONTAINER_ID temporaryidentifiers to form complete SI message(s) for the particular neighborcell associated with the TFI and CONTAINER_ID. For example, the storedSI message(s), or portion(s) thereof, used for combining at block 1440may have been obtained by decoding PNCD messages received via the PACCH140 in the same radio block period, one or more previous radio blockperiods, or any combination thereof. Next, operation of the process 1400proceeds to block 1410 and subsequent blocks, as described above.

Next, operation of the process 1400 proceeds to block 1445. The process1400 also reaches block 1445 if, at block 1430, the channel monitor 1005determines that a received message is not a PNCD message. At block 1445,the channel monitor 1005 determines whether the received message is atype of message related to the provisioning of neighbor cell informationand that includes neighbor cell identification information, such as aPCCC, PCCO, PSHO or PNCD message containing cell identificationinformation. If the channel monitor 1005 determines that the receivedmessage is a PCCC, PCCO, PSHO or PNCD message containing cellidentification information (block 1445), then at block 1450 the messagedecoder 1010 included in the MS 125 decodes the PCCC/PCCO/PSHO/PNCDmessage received by the channel monitor 1005 regardless of which MS wasthe intended recipient of the PCCC/PCCO/PSHO/PNCD message. For example,with reference to FIGS. 7-8, at block 1450 the message decoder 1010decodes the TFI and CONTAINER_ID (and/or other) temporary identifiesincluded in the received PCCC/PCCO/PSHO/PNCD message. Additionally, atblock 1450 the message decoder 1010 decodes the BSIC and ARFCN includedin the received PCCC/PCCO/PSHO/PNCD message. Then, at block 1455 themessage decoder 1010 uses the information decoded at block 1450 toidentify stored neighbor cell SI messages associated with a particularthe TFI and CONTAINER_ID as corresponding to a particular neighbor cellidentified by the BSIC and ARFCN. As described above, the MS 125 canthen use the stored neighbor cell SI messages associated with particularneighbor cells in various mobility procedures, such as cell reselection,CRE, etc. Next, operation of the process 1400 proceeds to block 1410 andsubsequent blocks, as described above.

Returning to block 1445, if the channel monitor 1005 determines that noPCCC, PCCO, PSHO or PNCD message containing cell identificationinformation has been received, then at block 1460 the message decoder1010 determines whether a time period has expired. The time periodexamined at block 1460 is used to specify a window of time during whichstored neighbor cell information can be combined with newly receivedneighbor cell information. For example, the temporary identifiers (e.g.,such as TFIs, CONTAINER IDs, etc.) used to associate neighbor cellinformation with a particular neighbor cell can be reassigned over time.As such, after some period of time, newly received neighbor cellinformation associated with a specific set of temporary identifiers maycorrespond to a different neighbor cell than stored neighbor cellinformation associated with those same temporary identifiers.Accordingly, if the time period has expired (block 1460), then at block1465 the message decoder 1010 discards any neighbor cell informationthat was being stored for combining with neighbor cell information themessage decoder 1010 was waiting to receive. Next, operation of theprocess 1400 proceeds to block 1410 and subsequent blocks, as describedabove.

An example process 1500 that may be performed to implement SI validityindication processing in any, some or all of the example MSs 125, 130and 135 of FIG. 1 or 6, or both, is illustrated in FIG. 11A. The process1500 may be executed at predetermined intervals (e.g., such as based ona multiple of a radio block period), based on an occurrence of apredetermined event (e.g., such as performance of certain mobilityprocedures, when certain measurement reports are to be prepared, etc.),as a background process, etc., or any combination thereof. Although theprocess 1500 could be used to implement any of the MSs 125, 130 and 135,for brevity and clarity, operation of the process 1500 is described fromthe perspective of implementation in the MS 125 of FIG. 6 for operationin the GERAN system 100 of FIG. 1.

With reference to the preceding figures, the process 1500 of FIG. 11Bbegins at block 1505 at which the process 1500 determines which neighborcell or cells are to be reported in a message to be sent to the network(e.g., such as via cell 1 of FIG. 1). For example, at block 1505 themessage may correspond to the PCCN message 718 of FIG. 3 and, thus, theneighbor cell to be reported is the target neighbor cell for cellreselection. As another example, at block 1505 the message maycorrespond to a measurement report in which measurements for one or moreneighbor cells are to be reported to the network.

Next, at block 1510 the process 1500 begins validity indicationprocessing for each neighbor cell to be included in the message beingsent to the network. For example, at block 1515 the process 1500discards any expired neighbor cell system information stored for thecurrent neighbor cell being processed. For example, the MS 125 may beconfigured to delete any neighbor cell system information that has beenstored in the memory unit 1415 for more than a specified time period(e.g., such as 30 sec.). Then, at block 1520 the process 1500 determineswhether an SI validity indication for the current neighbor cell beingprocessed was already sent in a previous message within a given timeperiod (e.g., such as 10 sec.). If the SI validity indication for thecurrent neighbor cell was previously sent within the time period (block1525), then at block 1530 the process 1500 determines whether there areadditional neighbor cells to process.

However, if the SI validity indication for the current neighbor cell wasnot previously sent within the time period (block 1525), then at block1535 the system information validity processor 1025 included in the MS125 clears the SI validity indication bitmap for the current neighborcell being processed. Then, at block 1540 the system informationvalidity processor 1025 determines whether a valid SI-1 message isstored for the current neighbor cell being processed. If a valid SI-1message is stored for the neighbor cell (block 1540), at block 1545 thesystem information validity processor 1025 sets the SI-1 bit in the SIvalidity indication bitmap that is used to indicate that a valid SI-1message for the neighbor cell is stored at the MS 125.

Next, at block 1550 the system information validity processor 1025determines whether a valid SI-3 message is stored for the currentneighbor cell being processed. If a valid SI-3 message is stored for theneighbor cell (block 1550), at block 1555 the system informationvalidity processor 1025 sets the SI-3 bit in the SI validity indicationbitmap that is used to indicate that a valid SI-3 message for theneighbor cell is stored at the MS 125. Then, at block 1560 the systeminformation validity processor 1025 determines whether a valid SI-13message is stored for the current neighbor cell being processed. If avalid SI-13 message is stored for the neighbor cell (block 1560), atblock 1565 the system information validity processor 1025 sets the SI-13bit in the SI validity indication bitmap that is used to indicate that avalid SI-13 message for the neighbor cell is stored at the MS 125.

Next, the message encoder 1030 included in the MS 125 encodes the SIvalidity indication bitmap for the neighbor cell currently beingprocessed in the message (e.g., such as a PCCN message, a measurementreport, etc.) to be sent to the network (if transmission of SI validityindications to the network is implicitly or explicitly authorized).Then, at block 1530 the process 1500 determines whether there areadditional neighbor cells to process. If there are additional neighborcells to process (block 1530), the process returns to block 1510 toobtain the next neighbor cell for validity indication processing.However, if there are no additional neighbor cells to process (block1530), the MS 125 sends the message including the encoded SI validityindication(s) to the network. The process 1500 then ends.

An alternative example process 1580 that may be performed to implementSI validity indication processing in any, some or all of the example MSs125, 130 and 135 of FIG. 1 or 6, or both, is illustrated in FIG. 11B.For comparison, the process 1500 of FIG. 11A processes a separatevalidity indication for each neighbor cell being reported, with each bitin the validity indication representing a status of a separate SImessage for the particular neighbor cell. In contrast, the process 1580of FIG. 11B processes a single validity indication bitmap in which eachbit represents a particular neighbor cell and indicates whether allnecessary SI messages (or a particular set or subset of SI messages) forthe neighbor cell are stored in the MS. Because the example processes1500 and 1580 of FIGS. 11A and 11B, respectively, include many elementsin common, like elements in FIGS. 11A and 11B are labeled with the samereference numerals. Detailed descriptions of these like elements areprovided above in connection with the process 1500 of FIG. 11A.

Turning to FIG. 11B, the process 1580 is described from the perspectiveof implementation in the MS 125 of FIG. 6 for operation in the GERANsystem 100 of FIG. 1, and operation of the process 1580 from block 1505through 1515 is substantially the same as for the process 1500 of FIG.11A. However, after block 1515 in FIG. 11B, the process 1580 proceeds toblock 1585 at which the system information validity processor 1025included in the MS 125 clears the particular bit of the SI validityindication bitmap corresponding to the current neighbor cell beingprocessed. For example, the SI validity indication bitmap may include anumber of bits (e.g., such as 6 bits), with each bit corresponding to arespective neighbor cell in a set of neighbor cells to be reported(e.g., such as up to 6 neighbor cells).

Next, at block 1590 the system information validity processor 1025determines whether the MS 125 has stored all of the neighbor cell's SImessages needed by the MS 125 to support mobility or other procedures.If all of the needed SI messages (e.g., such as a specified set orsubset of SI messages) for the current neighbor cell being processed arestored in the MS 125 (block 1590), then at block 1595 the systeminformation validity processor 1025 sets the particular bit of the SIvalidity indication bitmap corresponding to the current neighbor cellbeing processed. The process 1580 then proceeds to block 1530 asdescribed above in connection with FIG. 11A.

An example process 1600 that may be performed to implement SI validityindication processing in the BSC 105 (possibly in conjunction with oneor more of the BTSs 110-120) is illustrated in FIG. 12. The process 1600may be executed at predetermined intervals (e.g., such as based on amultiple of a radio block period), based on an occurrence of apredetermined event (e.g., such as when UL messages are received), as abackground process, etc., or any combination thereof. Operation of theprocess 1600 is described from the perspective of implementation in theBSC 105 of FIG. 9 for operation in the GERAN system 100 of FIG. 1.

With reference to the preceding figures, the process 1600 of FIG. 12begins at block 1605 at which the BSC 105 receives UL messages blocksfrom one or more MSs, such as the MS 125. Next, at block 1610 theprocess 1600 determines whether a message containing one or more SIvalidity indications has been received. When a message containing SIvalidity indication(s) is received (block 1610), at block 1615 thesystem information validity decoder 1305 included in the BSC 105 decodesthe one or more SI validity indications for the respective one or moreneighbor cells reported in the message received at block 1605. Then, foreach reported neighbor cell (block 1620), the system informationvalidity decoder 1305 determines whether the decoded SI validityindication bitmap being processed contains any bits set to indicate thata corresponding valid SI message for the current neighbor cell is storedat the MS 125, or a bit to indicate that all needed SI messages (e.g.,such as a specified set or subset of SI messages) for the currentneighbor cell are stored at the MS 125.

Next, at block 1630 the message scheduler 1310 schedules subsequentsending of PNCD messages containing neighbor cell information to the MS125 based on the SI validity indication(s) decoded by the systeminformation validity decoder 1305 at block 1625. For example, if thedecoded SI validity indication has one or more SI bits that were not setto thereby indicate that the respective one or more SI messages for thecurrent cell are not stored at the MS 125, then at block 1630 themessage scheduler 1310 schedules one or more PNCD messages to send thesecorresponding one or more SI message to the MS 125. In other words, atblock 1630 the message scheduler 1310 can forego sending (or, in otherwords, omit sending) PNCD messages containing SI messages reported asvalid in the SI validity indication bitmap decoded at block 1630.

Next, at block 1635 the process 1600 determines whether all reportedneighbor cells have been processed. If all reported neighbor cells havenot been processed (block 1635), control returns to block 1620 andblocks subsequent thereto. However, if all reported neighbor cells havebeen processed (block 1635), the BSC 105 causes any PNCD message(s) tobe sent to the MS 125 as scheduled at block 1630. The process 1600 thencontinues as shown.

As another example, the techniques to monitor channels for neighbor cellinformation described herein can be used to determine system informationfor a serving cell in communication with an MS in addition to, or as analternative to, determining system information for one or more neighborcells. For example, in a circuit switched (CS) voice call, or a DTMcall, an MS, such as the MS 125, can be configured to monitor a PACCH,such as the PACCH 140, for non-distribution packet serving cell data(PSCD) messages containing serving cell SI messages being conveyed toanother MS. Such monitoring can be performed in addition to, or as analternative to, monitoring for PNCD messages containing neighbor cell SImessages being conveyed to another MS. Monitoring for PSCD messagescontaining SI messages for the serving cell can be beneficial in manyscenarios. For example, the MS 125 may not yet possess systeminformation for its serving cell, such as in the case of arriving to theserving cell by means of a handover. Also, in the case of a radio linktimeout or failure, the MS 125 may determine that call re-establishmentshould be initiated to its serving cell, rather than a different cell,such as in the case of the radio link timeout or failure being caused byhigh interference specific to the resources assigned to the MS 125. Inthese and other examples, the MS 125 can use the techniques describedherein to obtain current system information for the serving cell bymonitoring PSCD messages addressed to other mobile stations.

Also, a conventional MS operating in a voice-only call typically is notconfigured to receive data via a PACCH. However, in at least someexample implementations, the MS 125 could be configured to receive anddecode message blocks conveyed via the PACCH 140 even though the MS 125is operating in a voice-only call and, thus, is not to receive anymessages addressed to itself via the PACCH 140. Additionally oralternatively, when operating in a mode supporting packet datacommunications, the MS 125 could be configured to receive and decodemessage blocks conveyed via the PACCH 140 even though the MS 125 isallocated to a different PACCH and, thus, is not to receive any messagesaddressed to itself via the PACCH 140. These example implementationsallow the MS 125 to utilize the techniques to monitor channels forneighbor cell information described herein even when not operating in amode supporting packet data communications and/or when not allocated tothe channel to be monitored.

To potentially reduce power consumption when implementing the techniquesdescribed herein, the MS 125 can be configured to trigger channelmonitoring for cell information under only certain conditions. Forexample, the MS 125 can trigger channel monitoring based on one or moreof the following criteria: (1) certain channel conditions being detectedin its serving cell, (2) signal strength and/or signal qualitymeasurements associated with a neighbor cell different from the servingcell, (3) detection of a received message block error (e.g., such as oneor more SACCH block errors), (4) occurrence of a cell change, etc.

As yet another example, the techniques to monitor channels for neighborcell information and the techniques to avoid transmission of redundantneighbor cell information described herein can be implemented in a GERANcommunication system conforming to the third generation partnershipproject (3GPP) specifications by appropriately modifying 3GPP TechnicalSpecification (TS) 44.060, V9.0.0 (May 2009), which is herebyincorporated by reference in its entirety. Example modifications to 3GPPTS 44.060 to support the example techniques to monitor channels forneighbor cell information and the example techniques to avoidtransmission of redundant neighbor cell information described hereininclude, but are not limited to, the following changes:

(I) Modify section 5.5.1.1a.1, “Neighbour Cell System InformationDistribution,” to indicate that a mobile station receiving neighbor cellsystem information in a PACKET NEIGHBOUR CELL DATA message which is notaddressed to it may store the information for up to 30 seconds andduring that period may use the information for initial access to thecorresponding neighbor cell.

(II) Modify section 8.3, “Procedure for measurement report sending inPacket Transfer mode,” to indicate that if the network indicates that itsupports reception of VALID_SI indications, the mobile station mayinclude a VALID_SI indication in the PACKET MEASUREMENT REPORT messageor PACKET ENHANCED MEASUREMENT REPORT message. Additionally, the mobilestation shall include this information in such a message if it has notsent this information in the last 10 seconds.

(III) Modify section 8.8.1, “Neighbour Cell System InformationDistribution,” to indicate that if a mobile station to which a PACKETNEIGHBOUR CELL DATA message was not addressed decodes the contents ofthe message, the container identity is determined by the combination ofTFI and CONTAINER_ID contained within the instances of the message. Sucha mobile station may combine complete system information messagesobtained from partially received containers received while in the samecell, if the neighbor cell associated with the containers is the same(e.g., as explicitly identified by the same ARFCN and BSIC). Note, theonly information from partially received containers that can be used isthat obtained from consecutive instances of PACKET NEIGHBOUR CELL DATAmessages (e.g., instances belonging to the same container withconsecutive CONTAINER_INDEX values) including the first instance (inwhich the CONTAINER_INDEX has a value of 0) within a container. Notealso that the inclusion of the ARFCN and BSIC in at least one instanceof a PACKET NEIGHBOUR CELL DATA message for a given neighbor cell allowsa mobile station to which the PACKET NEIGHBOUR CELL DATA message was notaddressed to make use of the contained system information. Because theMS can identify different instances of PACKET NEIGHBOUR CELL DATAbelonging to the same container by means of the TFI and CONTAINER_IDfields, it is not necessary to include the ARFCN and BSIC in every suchinstance.

(IV) Modify section 8.8.2, “Cell Change Notification procedure,” toindicate that if a proposed target cell of cell reselection is a GSMcell, the network has indicated it supports the VALID_SI indication andthe PACKET CELL CHANGE NOTIFICATION contains measurement reports for oneor more GSM cells, the mobile station shall include the VALID_SIindication for as many GSM cells as it is able to report. If the targetcell is a GSM cell, the inclusion of this information shall takeprecedence over the inclusion of measurement reports for non-GSM cells.Note, if the mobile has indicated by means of the VALID_SI indicationthat it has received the necessary system information for the targetcell, the network may omit sending PACKET NEIGHBOUR CELL DATA messagescontaining that system information.

(V) Modify section 11.1.1.2, “Non-distribution messages,” to indicatethat, unless explicitly permitted, a non-distribution message shall beignored by any MS not identified by the address information contained inthe non-distribution message.

(VI) Modify section 11.2.3a, “Packet Cell Change Notification”, toinclude VALID_SI indication(s) in the contents of a PACKET CELL CHANGENOTIFICATION message. For example, define a three (3) bit VALID_SI fieldin which, if set to ‘1,’ a bit within this field indicates that themobile station has currently stored system information which wasreceived in the last 30 seconds for the respective neighbor cellidentified in the cell PACKET CELL CHANGE NOTIFICATION message. For eachinstance of the field, bit 0 refers to SI-1, bit 1 to SI-3 and bit 2 toSI-13. Alternatively, define a six (6) bit VALID_SI_BITMAP in which, ifset to ‘1,’ a bit within this field indicates that the mobile stationhas currently stored a specified set or subset of system information(SI-3, SI-13 and, if applicable, S-1) for a particular neighbor cellwhich was received in the last 30 seconds for the respective cellidentified in the cell PACKET CELL CHANGE NOTIFICATION message (i.e.,bit 0 corresponds to the first cell listed in the PACKET CELL CHANGENOTIFICATION message, etc.). This field shall not be included if no GSMcells were reported in the PACKET CELL CHANGE NOTIFICATION message.

(VII) Modify section 11.2.9, “Packet Measurement Report,” includeVALID_SI indication(s) (e.g., as defined in the modification to section11.2.3a) in the contents of a PACKET MEASUREMENT REPORT message.

(VIII) Modify section 11.2.9e, “Packet Neighbour Cell Data,” to indicatethat, although the PACKET NEIGHBOUR CELL DATA message is a nondistribution message, mobile stations which are not identified by theaddress part may decode and act upon the non distribution part of thismessage.

(IX) Modify section 12.24, “GPRS Cell Options,” to include aVALID_SI_SUPPORT bit field in the GPRS cell options information element(where GPRS refers to “general packet radio service”). For example, theVALID_SI_SUPPORT could be a one (1) bit field that indicates whether thecell supports the VALID_SI_BITMAP/VALID_SI field in the PACKETMEASUREMENT REPORT, PACKET CELL CHANGE NOTIFICATION and PACKET ENHANCEDMEASUREMENT REPORT. For example, a value of ‘0’ indicates that the celldoes not support the VALID_SI_BITMAP/VALID_SI field, whereas a value of‘1’ indicates that the cell supports the VALID_SI_BITMAP/VALID_SI field.

FIG. 13 is a block diagram of an example processing system 1700 capableof implementing the apparatus and methods disclosed herein. Theprocessing system 1700 can be, for example, a mobile station processingplatform, a network element processing platform, a server, a personalcomputer, a personal digital assistant (PDA), an Internet appliance, amobile phone, or any other type of computing device.

The system 1700 of the instant example includes a processor 1712 such asa general purpose programmable processor. The processor 1712 includes alocal memory 1714, and executes coded instructions 1716 present in thelocal memory 1714 and/or in another memory device. The processor 1712may execute, among other things, machine readable instructions toimplement the processes represented in FIGS. 10-12. The processor 1712may be any type of processing unit, such as one or more microprocessorsfrom the Intel® Centrino® family of microprocessors, the Intel® Pentium®family of microprocessors, the Intel® Itanium® family ofmicroprocessors, and/or the Intel® XScale® family of processors, one ormore microcontrollers from the ARM® family of microcontrollers, the PIC®family of microcontrollers, etc. Of course, other processors from otherfamilies are also appropriate.

The processor 1712 is in communication with a main memory including avolatile memory 1718 and a non-volatile memory 1720 via a bus 1722. Thevolatile memory 1718 may be implemented by Static Random Access Memory(SRAM), Synchronous Dynamic Random Access Memory (SDRAM), Dynamic RandomAccess Memory (DRAM), RAMBUS Dynamic Random Access Memory (RDRAM) and/orany other type of random access memory device. The non-volatile memory1720 may be implemented by flash memory and/or any other desired type ofmemory device. Access to the main memory 1718, 1720 is typicallycontrolled by a memory controller (not shown).

The computer 1700 also includes an interface circuit 1724. The interfacecircuit 1724 may be implemented by any type of interface standard, suchas an Ethernet interface, a universal serial bus (USB), and/or a thirdgeneration input/output (3GIO) interface.

One or more input devices 1726 are connected to the interface circuit1724. The input device(s) 1726 permit a user to enter data and commandsinto the processor 1712. The input device(s) can be implemented by, forexample, a keyboard, a mouse, a touchscreen, a track-pad, a trackball,an isopoint and/or a voice recognition system.

One or more output devices 1728 are also connected to the interfacecircuit 1724. The output devices 1728 can be implemented, for example,by display devices (e.g., a liquid crystal display, a cathode ray tubedisplay (CRT)), by a printer and/or by speakers. The interface circuit1724, thus, typically includes a graphics driver card.

The interface circuit 1724 also includes a communication device such asa modem or network interface card to facilitate exchange of data withexternal computers via a network (e.g., an Ethernet connection, adigital subscriber line (DSL), a telephone line, coaxial cable, acellular telephone system, etc.).

The computer 1700 also includes one or more mass storage devices 1730for storing software and data. Examples of such mass storage devices1730 include floppy disk drives, hard drive disks, compact disk drivesand digital versatile disk (DVD) drives. The mass storage device 1730may implement the memory unit 1015. Alternatively, the volatile memory1718 may implement the memory unit 1015.

As an alternative to implementing the methods and/or apparatus describedherein in a system such as the device of FIG. 13, the methods and orapparatus described herein may be embedded in a structure such as aprocessor and/or an ASIC (application specific integrated circuit).

Finally, although certain example methods, apparatus and articles ofmanufacture have been described herein, the scope of coverage of thispatent is not limited thereto. On the contrary, this patent covers allmethods, apparatus and articles of manufacture fairly falling within thescope of the appended claims either literally or under the doctrine ofequivalents.

What is claimed is:
 1. A method for a first mobile station to determinecell information for a first cell, the method comprising: monitoring achannel for messages containing cell information; receiving a firstmessage via the monitored channel and addressed to a second mobilestation, the first message including first cell information; storing thefirst cell information for a time period after receiving the firstmessage; using a first identifier and a second identifier included inthe first message to obtain, from a second message conveyed via themonitored channel, an identity of a first neighbor cell in a pluralityof cells, the first identifier to indicate the first message isaddressed to the second mobile station and the second identifier toindicate the first cell information corresponds to a plurality ofneighbor cell information associated with the first neighbor cell,wherein the second message includes a third identifier, and wherein themethod further comprises: associating the first cell information withthe first neighbor cell if the third identifier matches the firstidentifier; and not associating the first cell information with thefirst neighbor cell if the third identifier does not match the firstidentifier.
 2. A method as defined in claim 1 further comprising:associating the first cell information with the first neighbor cell ifthe first and second messages are associated with at least one of a samereceived timeslot index or a same pair of received timeslot indices; andnot associating the first cell information with the first neighbor cellif the first and second messages are not associated with at least one ofthe same received timeslot index or the same pair of received timeslotindices.
 3. A method for a first mobile station to determine cellinformation for a first cell, the method comprising: monitoring achannel for messages containing cell information; receiving a firstmessage via the monitored channel and addressed to a second mobilestation, the first message including first cell information; storing thefirst cell information for a time period after receiving the firstmessage; using a first identifier and a second identifier included inthe first message to obtain, from a second message conveyed via themonitored channel, an identity of a first neighbor cell in a pluralityof cells, the first identifier to indicate the first message isaddressed to the second mobile station and the second identifier toindicate the first cell information corresponds to a plurality ofneighbor cell information associated with the first neighbor cell,wherein the second message includes a third identifier, and wherein themethod further comprises: associating the first cell information withthe first neighbor cell if the first and third identifiers indicate thatthe respective first and second messages are addressed to the secondmobile station; and not associating the first cell information with thefirst neighbor cell if the first and third identifiers indicate that therespective first and second messages are addressed to different mobilestations.
 4. A method for a first mobile station to determine cellinformation for a first cell, the method comprising: monitoring achannel for messages containing cell information; receiving a firstmessage via the monitored channel and addressed to a second mobilestation, the first message including first cell information; storing thefirst cell information for a time period after receiving the firstmessage; and storing a plurality of system information messagesassociated with a neighbor cell, the plurality of system informationmessages included in a plurality of packet neighbor cell data (PNCD)messages received via a plurality of monitored channels during aplurality of radio block periods, the plurality of PNCD messagesaddressed to one or more mobile stations including the second mobilestation but not including the first mobile station, wherein an orderingof the system information messages contained in the PNCD messages isvaried among the plurality of radio block periods.
 5. A method for afirst mobile station to determine cell information, the methodcomprising: monitoring a channel for messages containing cellinformation; receiving a first message via the monitored channel andaddressed to a second mobile station, the first message including firstcell information corresponding to system information broadcast by afirst neighbor cell of a network, the first message not being addressedto the first mobile station; and storing, at the first mobile station,the first cell information included in the first message addressed tothe second mobile station and not addressed to the first mobile stationfor a time period after receiving the first message to permit the firstmobile station to combine the first cell information with other cellinformation, wherein the monitored channel corresponds to a packetassociated control channel (PACCH).
 6. A method as defined in claim 5wherein the first message corresponds to a first packet neighbor celldata (PNCD) message.
 7. A method as defined in claim 5 furthercomprising using the first cell information during the time period toaccess at least one of the first neighbor cell or a second neighborcell.
 8. A method as defined in claim 5 further comprising: using afirst identifier and a second identifier included in the first messageto obtain, from a second message conveyed via the monitored channel, anidentity of the first neighbor cell, the first identifier to indicatethe first message is addressed to the second mobile station and thesecond identifier to indicate the first cell information corresponds toa plurality of neighbor cell information associated with the firstneighbor cell; and associating the first cell information with the firstneighbor cell.
 9. A method as defined in claim 8 wherein the identity ofthe first neighbor cell comprises a base station identifier and achannel number.
 10. A method as defined in claim 8 further comprisingcombining the first cell information with second cell informationincluded in a third message conveyed via the monitored channel andincluding the first identifier and the second identifier.
 11. A methodas defined in claim 10 wherein the first message corresponds to a firstPNCD message, the third message corresponds to a second PNCD message,and the second message corresponds to at least one of a packet cellchange continue (PCCC) message, a packet cell change order (PCCO)message, a packet system hand over (PSHO) command message or a thirdPNCD message.
 12. A method as defined in claim 5 further comprising:storing second cell information included in a second message receivedvia the monitored channel and addressed to the second mobile station;and combining the first cell information and the second cell informationto determine system information associated with the first neighbor cell.13. A tangible machine readable storage device or storage diskcomprising machine readable instructions which, when executed, cause afirst machine to at least: monitor a packet associated control channel(PACCH) for messages containing neighbor cell information; and store, atthe first machine, first neighbor cell information included in a firstpacket neighbor cell data (PNCD) message, which is received via themonitored PACCH and addressed to a second machine that is to receivedata on the monitored PACCH, for a time period after determining thefirst PNCD message includes the first neighbor cell information topermit the first machine to combine the first cell information withother cell information, the first neighbor cell informationcorresponding to system information broadcast by a first neighbor cell,the first PNCD message being addressed to the second machine and notbeing addressed to the first machine.
 14. A first mobile stationcomprising: a channel monitor to monitor a channel for messagesaddressed to one or more other mobile stations, the messages containingneighbor cell information corresponding to system information broadcastby one or more neighbor cells of a network, the monitored channelcorresponding to a packet associated control channel (PACCH); and amessage decoder to: decode and store first neighbor cell informationincluded in a first message, received via the monitored channel andaddressed to a second mobile station but not addressed to the firstmobile station, for a time period after determining the first messageincludes the first neighbor cell information; decode and store secondneighbor cell information included in a second message received via themonitored channel and addressed to the second mobile station but notaddressed to the first mobile station; and combine the first neighborcell information and the second neighbor cell information to determinesystem information associated with a first neighbor cell in a pluralityof neighbor cells.
 15. A first mobile station as defined in claim 14wherein the first message corresponds to a first packet neighbor celldata (PNCD) message and the second message corresponds to a second PNCDmessage.
 16. A first mobile station as defined in claim 14 wherein themessage decoder is further to: use a first identifier and a secondidentifier included in the first message to obtain, from the secondmessage received via the monitored channel, an identity of the firstneighbor cell, the first identifier to indicate the first message isaddressed to the second mobile station and the second identifier toindicate the first neighbor cell information corresponds to a pluralityof neighbor cell information associated with the first neighbor cell;and associate the first cell information with the first neighbor cell.17. A mobile station comprising: a channel monitor to monitor a channelfor messages containing neighbor cell information; and a message decoderto: decode and store first neighbor cell information included in a firstmessage, received via the monitored channel and addressed to a secondmobile station, for a time period after determining the first messageincludes the first neighbor cell information; decode and store secondneighbor cell information included in a second message received via themonitored channel and addressed to the second mobile station; combinethe first neighbor cell information and the second neighbor cellinformation to determine system information associated with a firstneighbor cell in a plurality of neighbor cells; use a first identifierand a second identifier included in the first message to obtain, fromthe second message received via the monitored channel, an identity ofthe first neighbor cell, the first identifier to indicate the firstmessage is addressed to the second mobile station and the secondidentifier to indicate the first neighbor cell information correspondsto a plurality of neighbor cell information associated with the firstneighbor cell; and associate the first cell information with the firstneighbor cell, wherein the message decoder is further to combine thefirst neighbor information and the second neighbor information when thefirst neighbor information and the second neighbor information have asame first identifier and a same second identifier.
 18. A mobile stationas defined in claim 17 wherein the first message corresponds to a firstpacket neighbor cell data (PNCD) message, and the second messagecorresponds to at least one of second PNCD message, a packet cell changecontinue (PCCC) message, a packet cell change order (PCCO) message or apacket system hand over (PSHO) command message.